Twins and Multiple Births

September 7, 2006
Howard Carp, MD
Howard Carp, MD

OBGYN.net Conference CoverageFrom First Congress on Controversies in Obstetrics, Gynecology & Infertility Prague CZECH REPUBLIC - October, 1999

Professor Howard Carp: "I'm sitting now with Dr. Dan Farine, who's the Director of Fetal Maternal Medicine at Mount Sinai Hospital in Toronto, Canada. He was the chairman of the session on twin pregnancy this morning. Dr. Farine?"

Dr. Dan Farine: "Thank you, Howard. It was actually a very pleasant session. The controversy was not that much in terms of arguing between the speakers about their approaches, it was more comprehensive in the sense that we had a few speakers that touched on different aspects of twinning. The first talk was actually quite provocative. It was given by Lewis Keith, who was the head of the Institution for Twin Studies in Chicago. Lewis presented his own personal experience with him and his twin brother that were labeled as monozygotic and dizygotic in four different ways over the years. What he brought up was the issue of zygosity from a different prospective, and the fact that the genetics of twinning could be different after conception so twins may be quite similar, but not perfectly similar, and there could be some delayed variability which is introduced after conception. This led us to into the discussion on how to diagnose monozygosity using new DNA technology. It was pretty clear that, number one, there is no gross standard and, number two, the more testing you're going to use, the more you're going to find twins that are not exactly identical."

Professor Howard Carp: "I found this very interesting because what you were saying is, rather than assuming that monozygotic twins were exactly the same genetically, psychologically, etc., as we assumed before, he was now talking about a new classification of monozygotic twins who were discordant for various other features."

Dr. Dan Farine: "Absolutely, and those features could be specifically genetic, diseases, or other conditions, so this is a new concept that kind of takes us from the dichotomy of monozygotic--dizygotic."

Professor Howard Carp: "And I understand there was also a lot of discussion on the ways to diagnose twins early on in pregnancy rather than diagnosing monozygotic and dizygotic twins at the time of delivery. That comes up with early ultrasound, about the ultrasonic signs of monozygosity, isn't that right?"

Dr. Dan Farine: "This was discussed by Israel Meizner, and what he did was actually lump together the data about ultrasound scanning and zygosity, which is actually crucial for the management of the pregnancy. He did a very nice summary of the early ultrasound data and the late ultrasound data leading obstetricians to the best diagnosis of zygosity. He also touched on other issues, like monoamniotic twins and conjoined twins, but the major issue was actually trying to determine zygosity using ultrasound scanning. What came out very, very clearly was that you need to scan those patients more than once, and preferably somewhere before the eighth week mark, then after the eighth week mark and at the second trimester, to get the optimal ultrasound data which allows you to determine zygosity."

Professor Howard Carp: "Yes. Could you also comment on the multiple pregnancy work and the iatrogenic causes of multiple pregnancy? There was some discussions on IVF, I understand - how many eggs were replaced in the uterus and, of course, did this influence the multiple pregnancy rate."

Dr. Dan Farine: "This actually came up several different times. It came up in the presentation of Lewis Keith. It came up again in the presentation of Issac Blickstein that actually made this as one of the determinants of how to deliver twins, and the fact that many of these patients are infertile. He used different technologies to get pregnant, and this modifies their perception and the obstetrician's perception. This culminated in a very heated discussion at the very end in terms of how many embryos should actually be implanted back into the uterus and whether it would be re-suited to two or to three. It was actually quite interesting to see Nick Fisk and Chervenak disagreeing, very politely but very firmly, and then hear the input from everybody else around the table and in the audience. It was also interesting to see the difference between people with reproductive endocrinology backgrounds. Dr. Insler discussed it in terms of the perspective of the endocrinologist infertility specialist, and he confronted those with the views of the maternal fetal medicine people on the panel that felt that having triplets carries major risks. Lewis Keith discussed the psycho-social issues, and he quoted the data from France that showed that many of the families of triplets are devastated by major social effects within the three years from the time of delivery. So it's not only just a pure medical issue, but also it also has psychological aspects."

Professor Howard Carp: "Was the place of reduction of triplets down to twin pregnancies discussed?"

Dr. Dan Farine: "I think that in a way we tried not to discuss it too extensively since there was another session devoted to that, but it certainly came up. I think that the most interesting way it came up was Nick's provocative statement that what you should do is either put back two eggs or put twenty back in and then have a reduction. So the issue of reduction also became quite extensive and served as a function of the next ethical issue in terms of how to approach each reduction from ethical perspectives, and he gave a very elegant overview of that issue."

Professor Howard Carp: "Yes, I understand from there that you went on to the more straightforward obstetric issues about twin-to-twin transfusion syndrome, and how you should, in fact, deliver twins in the labor ward. Do you have some comments on that?"

Dr. Dan Farine: "I think Nick has given an excellent overview of the issue of the twin-to-twin transfusion, and it was very provocative. I think that the first point that he made was the fact that we have seven different therapy modalities indicated, and none of them are perfect. He then looked at our ability to diagnose the twin-to-twin transfusion as well, and he compared his own data and other centers' data in terms of laser versus amnio-reduction, and what would be the right indication to intervene. I think he gave a very well balanced overview of the issues. We are still pretty far away from where we should be, and the maternal fetal medicine community is trying to overcome some of those hurdles by having conjoint efforts as multi-center studies looking at specific modalities of therapy like fenestration of the membranes."

Professor Howard Carp: "Thank you very much, Dr. Farine."

Dr. Dan Farine: "Thank you."